The present invention relates to a self-heating or a self-cooling container.
There have been many proposals for self-heating or self-cooling beverage containers. WO 96/29255, for example, discloses a can having the same external dimensions and shape as conventional beverage cans, but having an indented base to define an external cavity in which means to cool or heat the contents of the can are received.
Heating or cooling of the contents of the can can be achieved by using two chemical reactants which are stable when separated, but which produce an exothermic reaction or an endothermic reaction when mixed. U.S. Pat. No. 5,626,022 shows just one example, from many, of an insert for a self-heating or self-cooling can which enables mixing of the reactants when required. This construction, as is common, utilises a breakable or pierceable barrier to separate the two reactants and spikes or other piercing means to break the barrier when their reaction is required to heat or cool the can.
As indicated, self-heating containers may utilise an exothermic reaction as the energy source to heat the contents of the container. Commonly, this exothermic reaction mixes quicklime (calcium oxide) and water to produce heat. The reaction also produces steam and heated air which could lead to a potentially dangerous pressure build-up unless vented from the container in some manner. However, calcium oxide, for example, is strongly hydroscopic and needs to be kept isolated from the atmosphere to ensure that it maintains its reactivity.
There is therefore a conflict between the need to seal the reactants from the atmosphere, and the need to avoid pressure build up upon the generation of vapour from the reaction. The present invention seeks to address this conflict.
According to the present invention there is provided a self-heating or self-cooling container comprising a tubular peripheral wall within which first and second separated cavities extend, the first cavity receiving the contents of the container, and the second cavity housing a heating or cooling mechanism, a first end member closing the first cavity, and a second end member closing the second cavity, wherein said second end member comprises a closure fastened onto the peripheral wall to close the second cavity, and wherein the closure carries or supports sealing means arranged to seal the second cavity to atmosphere but to allow excess pressure in the second cavity to be vented.
With a self-heating or self-cooling container of an embodiment of the invention, vapour produced by the heating or cooling mechanism, for example, a high pressure gas produced by a cooling mechanism, or the steam and/or hot air produced by an exothermic heating reaction, is able to vent from the second cavity by way of the sealing means. However, this sealing means acts to seal the second cavity to atmosphere and hence keeps the reactants of the heating or cooling mechanism in good condition prior to use. It will appreciated that, in effect, the sealing means act as a one-way valve.
A self-heating or a self-cooling container of an embodiment of the invention may incorporate any heating or cooling mechanism. Various arrangements are described, for example, in WO 96/29255. In a preferred embodiment, the heating or cooling mechanism comprises a first chemical reactant and a second chemical reactant received within the second cavity of the container. The chemical reactants are kept apart until heating or cooling of the contents of the container is required. The chemical reactants are protected from degradation until required by the closure and its sealing means.
The closure may be of any required construction. For example, the closure may be as described in co-pending International application No. PCT/GB00/00700. The closure, as described in that earlier International application, may incorporate a container for one of the reactants of the heating or cooling mechanism. Alternatively, the closure may be configured as a simple closure for the second cavity. In an embodiment, said closure is provided with a peripheral rim which is appropriately shaped to engage onto the peripheral wall to close the second cavity, and said sealing means is a continuous sealing member carried by or supported on said closure internally of its peripheral rim.
For example, said continuous sealing member engages around an opening of said second cavity. In addition, said continuous sealing member may engage with said peripheral wall and/or with any other appropriate part of said container.
In one embodiment, said sealing member is an annular sealing flange connected to said closure and movable to enable excess pressure to be vented from the second cavity.
For example, the closure may be made of plastics material, and said sealing flange integrally formed therewith.
The shape and construction of the annular sealing flange may be chosen as required. For example, the flange may be connected to the closure at hinge means whereby the flange is movable to vent excess pressure. The hinge means may be formed by a narrowed or waisted portion of the sealing flange.
Alternatively, the sealing flange may be shaped or waisted along its length to provide for the flexibility or movement to vent the excess pressure.
In one embodiment, said sealing member is an annular, sealing ring supported to seal the second cavity, and deformable to enable excess pressure to be vented from the second cavity.
The sealing ring, for example, may be made of a squashable or deformable material such as plastics material or rubber. Thus, the sealing ring may normally have the volume to seal the second cavity against atmosphere, but may be arranged to be squashed to a smaller volume by excess pressure in the external cavity whereby the excess pressure is vented.
It will be appreciated that any construction which enables the sealing means to act in a one-way manner may be utilised. It is required, as set out above, that the sealing means seal the second cavity against atmosphere, but allows venting of excess pressure from the second cavity. In this respect, it is generally required that the sealing means flex, deform or move to vent pressure in excess of 2 psi.
The embodiments particularly described show sealing means at the periphery of the closure which are continuous in structure. However, it will be appreciated that the sealing means may be differently located and/or may be discontinuous or interrupted. If required one or more individual sealing members may be provided.
In WO 96/29255, the second cavity of the container, which supports the heating or cooling mechanism, extends within the first cavity in which the container contents are received. It will be appreciated that the invention is not limited to any particular form or structure of self-heating or self-cooling container and is applicable, for example, to a container in which the second cavity surrounds the first cavity which houses the contents. Alternatively, the first and second cavities may extend side by side.
Although it is general preferred that the end member for the first cavity is at the opposite end of the peripheral wall to that for the second cavity, this not essential. The first and second end members may, if required, both be arranged at the same end of the peripheral wall.
A self-heating or self-cooling container of the invention may be used to contain any contents which may require cooling or heating. Thus, not only is the container suitable for beverages, it may alternatively be used for foodstuffs or medicines.